The HTTP Transport provides connectivity to CICS Web Support. It is used along with the Mainframe Adapter Runtime to allow java clients to run CICS programs over HTTP.
CICS Web Support is a standard feature of CICS Transaction Server, it behaves as an HTTP/HTTPS server. Chttprt provides a C/370 program that behaves as a CGI and ultimately links to the target CICS program.
Chttprt does not use any of the CICS Web Service capabilities, just the HTTP transport. It uses an optimized binary content which reduces the HTTP payload to a minimum and avoids any character set translations on the host.
On the java side, Chttprt is based upon Apache HTTPClient.
For instructions on how to install and configure this transport follow this link.